Linguistic expressions of modality allow speakers to abstract away from the ‘here and now’ and talk about unrealized possibilities, uncertainty and chance, preferences and obligations, causes and explanations. These and related notions are crucially involved in plans and decisions, predictions and explanations, even emotional states like regret and relief. Modal expressions therefore have long been recognized as offering fascinating gateways to understanding these fundamental cognitive abilities.

In formal semantics, the standard framework for the analysis of modal expressions (and related ones like conditionals) was developed in the possible-worlds tradition of philosophical logic. The most influential version of this framework is due to Kratzer’s seminal work. Kratzer adopted from modal logic the basic idea of analyzing modal expressions in terms of quantification over possible worlds. The crucial insight underlying her analysis of the languages she studied (mostly German and English) was that the main contrasts in their inventories of modal expressions could be captured in terms of two parameters: the domain of quantification (determining the modal flavor - epistemic, deontic, etc. - and implemented in her system in terms of the interplay between modal base and ordering source), and the modal force (degrees of necessity and possibility, given by the interplay between modal operators and the ordering source). The resulting two-dimensional classification was an enormous achievement in its simplicity, elegance and coverage. In the ensuing decades, while the framework was applied in detailed analyses of a wide range of modal expressions in various languages, the confrontation of the formal framework with empirical phenomena has continued to motivate calls for augmentations or adjustements. There has also been increasing debate over the limits of a truly uniform analysis of all modal flavors - in particular, dispositional, teleological and epistemic modals have been shown to each require specific tools. Among deontic and teleological necessity modals, a distinction between strong and weak ones has been proposed. For deontic modal auxiliaries, the distinction between descriptive and performative uses has attracted considerable attention. In recent years, these long-standing debates have received fresh impulses and new directions thanks to a surge in highly relevant, high-quality contributions from theoretically well-informed investigations of typologically different understudied languages. In particular, recent investigations have challenged the distinction between lexically encoded quantificational force and (largely) context dependent modal flavors. The distinction between epistemic modals and evidential markers has been subjected to scrutiny, further questioning whether all modal verbs contribute to the (truth-conditional) at-issue content of an utterance.